“Over the eight-week study, participants had the cortisol in their saliva measured before and after the nature experience four separate times,” according to the article in Fast Company. “What the researchers gathered from all that data was that time in nature definitively reduces stress. The dip may start immediately, but only at 20 minutes does the data show the cortisol drop to be significant. The drop continues, topping out around 30 minutes, but cortisol levels will continue declining for as long as an hour.”

Hunter added that spending more than 30 minutes would be increasingly beneficial up to the first hour.

And the American Heart Association concurs, “Spending time in nature can help relieve stress and anxiety, improve your mood, and boost feelings of happiness and wellbeing… your brain benefits from a journey back to nature. The constant stimulation [of an urban environment] puts stress on brains that evolved in more tranquil environments. Nature presents scenes that gently capture your attention instead of suddenly snatching it, calming your nerves instead of frazzling them.”

Hunter said her small study of 36 urban dwellers did not require a minimum area of green space, it simply had to qualify as nature in the eye of the beholder.